NAT Port Mapping Protocol (NAT-PMP)

This document describes a protocol for automating the process of creating Network Address Translation (NAT) port mappings. Included in the protocol is a method for retrieving the external IPv4 address of a NAT gateway, thus allowing a client to make its external IPv4 address and port known to peers that may wish to communicate with it. From 2005 onwards, this protocol was implemented in Apple products including Mac OS X, Bonjour for Windows, and AirPort wireless base stations. In 2013, NAT Port Mapping Protocol (NAT-PMP) was superseded by the IETF Standards Track RFC "Port Control Protocol (PCP)", which builds on NAT-PMP and uses a compatible packet format, but adds a number of significant enhancements.